Use is currently made in the automobile industry of telescoping systems operating as pneumatic or gas springs for assisting the opening of raisable horizontally-hinged car-body covers such as a rear gate or a front hood. Such gas springs basically comprise a plunger rod which gastightly penetrates into a cylinder filled with a gas under pressure such as nitrogen: upon introduction of the plunger rod inside the cylinder, there occurs a supplemental compression of the gas which acts on the inner free end of the rod and tends to project the latter outside the cylinder.
A description of the structure and operation of an apparatus of this type is given in Allinquant et al. 4089512 which further describes a specific sealing system fitted at one end of the cylinder and traversed by the plunger rod.